High-altitude balloons, filmy bags of helium floating at altitudes that no known airplane can sustain, have attracted increasing attention as the US Air Force has looked at "near space" - above air traffic, with long lines of sight - as an operating regime. One snag: balloons go whither the wind blows, payload and all.

A USAF-sponsored project to deal with that problem, Talon Topper, has been under way for several years, and a critical demonstration has just been disclosed. Contractor Near Space Corporation - based in Oregon - has successfully tested a Payload Return Vehicle (PRV), a radical lifting-body glider that can safely descend from very high altitudes to a controlled landing, returning an instrument package to a desired location.

Alert readers will instantly recognize the PRV for what it is - a close relative of the Facetmobile, the all-flat-surface personal aircraft designed and test-flown by Barnaby Wainfan, who is employed in civilian life as as an ace aerodynamicist at Northrop Grumman.

Important aspects of the design include the ability to stay under control in a Mach 0.98 dive (don't try that with a conventional glider design), very light weight (useful for something carried by a balloon) and a shape that readily accommodates large payloads and antennas. It also has a very low stalling speed for easy and safe recovery. Faceting is not there for stealth but to make the aircraft easy to build.

Balloon-borne skysats - lofted to high altitudes where winds are gentle - provide cheap persistent platforms for communications or surveillance systems.